1. Field of the Invention
The present invention relates to image processing, and more specifically, to one-dimensional feature enhancement.
2. Description of the Related Art
A pointing device such as mouse is a standard peripheral for a computer system. A mechanical mouse typically has rollers, or wheels, that contact a rubber-surfaced steel ball at the equator thereof and convert the rotation of the ball into electrical signals. The mechanical mouse has a number of shortcomings such as deterioration or damage to the surface of the mouse ball and mouse pad, resulting form the mechanical construction and operation thereof that rely to a significant degree on a fairly delicate compromise about how mechanical forces are developed and transferred. An optical mouse utilizes optical and electronic method to compute the movement of the mouse, is a popular replacement for the mechanical mouse. Compared with the conventional mechanical mouse, an optical mouse offers better reliability and performance. Thus optical pointing devices have captured significant market share.
An optical mouse typically has a logical operation circuit and a Complementary Metal Oxide Semiconductor (CMOS) photosensing array comprising photo detectors. The CMOS photosensing array sequentially captures images of the area in which optical mouse moves and generates digital signals representing the captured image.
Images captured by the photo detectors are typically different from the real images as the captured images are distorted by both the external environment and internal signal processing and noise. The distortion of the captured image makes identifying the image in later stages of processing difficult. Therefore, appropriate actions for correcting the captured digital images are required. Examples of correction methods are image restoration, image enhancement, information extraction, link to database, and Geometric Information System (GIS). By performing correction to the captured image, the image becomes clearer and can be more easily recognized, furthermore, the similarity between the captured and real images can also be increased. Image enhancement corrects the digital image by enhancing particular features in the image. Commonly used image enhancement techniques are edge enhancement, contrast stretch, and feature extraction.
Digital images are composed of resolution cells with finite dimensions, and the edges of the image are usually blurry after the extraction process. The edge enhancement technique is an image enhancement method that clarifies the image outlines by generating spatial derivatives or digital image gradients.
The contrast stretch technique enlarges the contrast range in the image to make the image look clearer. The technique stretches each original digital value to a corresponding full range digital value according to a specific stretching ratio. A common contrast stretch technique is called linear contrast stretching, which transforms the largest recorded value to a largest allowable digital value, the smallest recorded value to a smallest allowable digital value, and transforms the remaining values according to a linear relationship. Gaussian stretching is another similar transformation technique, which assumes the distribution of the digital values is a bell shape.
Conventional image enhancement techniques correct digital images using a two-dimensional computation. However, the cost and power required for implementing two-dimensional computation in the integrated circuit are comparatively large due to the large data load and complicated computations. The present invention thus provides a simplified image enhancement method for enhancing features in digital images through one-dimensional computation.